1. Field of the Invention
The present invention relates to fabrication of abrasive tools and more particularly it relates to a composition for making the working portion of the tool based on, for example, diamond, cubic boron nitride and other superhard materials.
The invention will prove most useful in grinding the hard-to-work materials such as heat-resistant and hard alloys, cemented and nitrided steels.
2. Prior Knowledge
Currently known are various compositions for fabricating abrasive tools with organic, metallic and ceramic binders.
However, the tools made of such compositions are unable to efficiently machine heat-resistant alloys and steels.
For example, the tools with organic binders while ensuring a satisfactory standard of the machined surface are characterized by a considerable specific consumption of diamonds which leads to high costs for machining materials.
Also known in the prior art are the attempts to increase the durability of the tool with organic binders by using metallic fillers consisting of metals with high electrical conductivity and a nonoxidized surface. In the opinion of their authors such compounds allow the tools to be used for electrochemical grinding which increases the stability of the tool.
However, such fillers consist, as a rule, of costly materials, e.g. silver (see U.S. Pat. Nos. 3,433,730, 3,547,609, British Pat. No. 1,137,965, FRG Pat. No. 1544643) and copper plated with gold or platinum (see British Pat. No. 1,177,854 FRG Pat. No. 1752504).
The tools with metallic binders likewise fail to ensure efficient machining of the above-mentioned materials since they cannot produce the requisite quality of machined surface.
The tools with ceramic binders used nowadays provide for a satisfactory level of machining but have an essential disadvantage in the form of a low resistance to wear.
The most promising in this respect is a composition containing an abrasive material, a metallic filler and an organic binder. For imparting electrical conductivity, said composition contains additives which destroy oxide films on the particles of the metallic filler, e.g. colophony and activated carbon (see Author's Certificate Specification USSR No. 537798). The use of the tools made of this comparatively cheap composition and capable of being used for electrochemical grinding have decreased the consumption of superhard abrasive materials.
At the same time the specific consumption of these abrasive compounds remains considerable to the present day.
An object of the present invention lies in eliminating the aforesaid disadvantages.